FORM OF THE CONDUCTANCE FUNCTION 101 



hydrolyzed to an appreciable extent at very low concentrations. In 

 case the limits approached differ for the acids and the bases, the meas- 

 urement of the conductance of very dilute salt solutions will be affected 

 by hydrolysis. It appears not impossible that the bases may approach 

 values of the mass-action constant lower than those of the acids. In 

 liquid ammonia solutions the ionization constants of the bases are much 

 lower than those of the acids. We might, therefore, expect that at con- 

 centrations approaching 10~ 5 normal the conductivity of the salt might 

 be appreciably affected by hydrolysis. This is almost certainly the case 

 with silver nitrate. The ionization constant of this base is approxi- 

 mately 2.5 X 10~ 4 at 25. This value is based on the solubility of a 

 saturated solution of silver oxide in water whose ionization has been 

 determined to be approximately 0.64. At 10~ 3 normal the conductance 

 of the silver nitrate solution would be affected to the extent of 0.7 per 

 cent due to hydrolysis. Until more accurate data are available on the 

 ionization of the strong acids and bases at low concentrations, the inter- 

 pretation of conductance measurements with salts at low concentrations 

 remains in doubt. 



5. Solutions of Formates in Formic Acid. It is evident, from the 

 considerations of the foregoing sections, that, as the concentration of an 

 electrolyte increases, the value of the function K' increases. In other 

 words, as the concentration of the electrolyte increases, the conductance 

 falls less rapidly than required by the simple mass-action relation. As 

 we have seen, if the simple mass-action law holds, then a plot of the 

 reciprocal of the equivalent conductance against the specific conductance, 

 or the ion concentration, yields a linear relation between the experi- 

 mentally determined points. Deviations from the mass-action law are 

 then, obviously, such that at high concentrations the points diverge from 

 a straight line toward the axis of specific conductances. In general, 

 therefore, these curves are concave toward the axis of specific con- 

 ductances. There are indeed a few cases in which the curves are convex 

 toward the axis of specific conductances, or, in other words, in which 

 the deviations from the mass-action relation are in the opposite direction. 

 This has been found to be the case with aqueous solutions of certain 

 weak organic acids whose viscosity is very high. Presumably this form 

 of the curve is due to the rapidly increasing viscosity of the solution at 

 higher concentration. The same form of curve has been found by 

 Schlesinger and his associates for solutions of formates in formic acid. 24 



* Schlesinger and Calvert, J. Am. Chem. 8oc. S3, 1924 (1911) ; Schlesinger and 

 Martin, J. Am. Chem. Soc. 36, 1589 (1914) ; Schlesinger and Coleman, J. Am. Chem. Soc. 38 

 271 (1916) ; Schlesinger and Mullinix, J. Am. Chem. Soc. 41, 72 (1919) ; Schlesinger and 

 Reed, J. Am. Chem. Soc. 41, 1921 (1919) ; Schlesinger and Bunting, J. Am. Chem. Soc. 11. 

 1934 (1919). 



